*{margin: 0;padding: 0px;}/*margin外边距合并问题，叠加重合问题，取最大！*/
body{
    background: url('../images/bg.jpg') no-repeat;  /*整张图铺满*/
    background-size: 100%;  /*宽高比*/
}
.container{
    position: relative;
    width: 985px;
    height: 550px;
    margin: 100px auto;
    /* background: red; */
}
.row{
    display: flex; /*弹性盒子模型，排列左往右*/
    justify-content: space-between;  /*行水平间隔自动平均*/
}
.item{
    opacity: 0.5;/* 或50% */
}
.current{
    opacity: 1; /* 不透明 */
}
.btn{
    position: absolute;
    background: url('../images/btn_bg.jpg') no-repeat;
    width: 200px;
    height: 68px;
    color: white;
    font-size: 20px;
    text-align: center;
    line-height: 68px;
    opacity: 0.95;
    cursor: pointer;
    left: 50%;
    top: 50%;
    transform: translate(-50%,-50%); /*  移动自身（左，上）50%*/
}
